Is this for tuning in park only? I know it says drive and park, but I have been getting some detonation around 1600-2000 rpm in any gear. Is my table too high?

Thanks,
Jason

 

Noone has any ideas?

 

try bringing it down 2* @ 1600 and 2k and/or adding a bit more fuel.

 

I'll try lowering it...thanks Nino.

 

try adding fuel if that doesnt work. Also, do it to both spark tables, idle and high octane (also low octane if you're running in SD). Id do one at a time to see which is the culprit though. If you're still getting some detenation, then try the high octane table, then the low if in sd, then add more fuel. Someone chime in if Im wrong.

 

You may still get the knock if what the sensors are picking up is drivetrain noise. Any way you can up the octane to check this?

 

Not here is ca...I could get some race gas, but I don't want to spend that much for a couple of gallons. I lowered 2*(per Nino), it helped. Now I get some knock at lower RPM's. So, I guess I need to lower it 2* from 400-800.

 

Hey Jason, any update?

 

I took out 2* starting at 1500 it seems fine, now I get some knock at 500. So, I am gonna take out 2* there, and see what happens. Thanks for suggestion Nino! Hey, are you in San Diego, or did you move? We need to have a send off cruise for you.

 

cool. glad i could help. Im still on deployment. Ill be there soon though Im not moving till the beginning of next year and yes, we do have to have a cruise!

 

For future reference, you can go to home depot or lowes and get a gallon of paint thinner (xylene or toluene) and put that in your tank to raise octane about 3 points.

 

base spark in drive is determined by vehicle speed. Speed has to be below a certain value before you are using that base spark table.
Once speed is above that value you are using the main spark table.

 

It's probably the crappy 98 knock sensors. I had to desensitize mine as I was picking up false knock all over the place. It's a known issue and I think that GM makes a fix that includes new knock sensors and a new harness for them.

 

Correct. I believe it's 4mph/10mph on the f-bodies. Once TP% exceeds ~1.2% or VSS exceeds 4mph or 10mph (depending on the OS), the car switches to the high/low octane tables. Remaining timing scenarios are determined by the base spark tables.

 

for reference, 2002 camaro,

It uses the base timing table in drive ANY TIME your foot is off the gas and tps % is less than 1.19.

The dissabling table for that via MPH is on table B5917. which from the factory is 255mph.

Trucks however have it not use all 4 tables all the time like on ours.

 

I will have to check this out. It does make sense. If not, why would the base spark table have so many cells for so many RPM's?

 

It is right, Im positive.

 

I sent you a PM about getting a new 98 PCM from you as the one that we have been shipping back and forth is still having the same problem for me. I kinda need one fast. If my core is worth anything to you, I will send it back to you.

 

I was just reading about doing that on the Corvetteforum...people said that does not work.


If it does work...can I do that on a regular basis, or is it a once in a while thing??? Is it one gallon per tank full?

Jason

 

some forced induction guys swear by it. F1 race cars run on a reduculous percentage of toluene, like 85%. Premium gas already contains 15% - 20% toluene right out of the pump.

You may be confusing it with acetone additive to increase milage and slightly raise octane, but this has been proven not to work.